CN110879080A - High-precision intelligent measuring instrument and measuring method for high-temperature forge piece - Google Patents
High-precision intelligent measuring instrument and measuring method for high-temperature forge piece Download PDFInfo
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Abstract
The invention discloses an intelligent measuring instrument for finishing the size and temperature distribution range of a high-temperature forging by adopting a non-contact method, and also discloses a measuring method thereof, which comprises the following steps: the method comprises the following steps of calibration of internal and external orientation elements of a 4K camera based on a three-dimensional control field, image preprocessing, a manual-assistance-based semi-automatic laser line endpoint pixel coordinate extraction technology, size measurement based on a binocular vision bionic technology, and infrared thermal imaging temperature measurement based on thermal radiation calibration. This patent measuring equipment has integrateed 4K big visual field image acquisition module, structure optical module, infrared imaging temperature measurement subassembly, and ultimate system has that human-computer interface is friendly, compact structure, and the reliability is high, and it is convenient to use, can effectively improve measurement of efficiency, guarantee personnel's safety.
Description
Technical Field
The invention belongs to the technical field of photoelectric measurement, and particularly relates to an intelligent measuring instrument for finishing the size and temperature distribution range of a high-temperature forging by adopting a non-contact means, and a measuring method thereof.
Background
The large forging is a key basic part for manufacturing national heavy equipment and constructing major engineering, and the manufacturing capacity and the manufacturing level of the large forging reflect the capacity and the level of manufacturing national heavy equipment and constructing major engineering. In the processing and forging of large-scale forgings, the size, shape and temperature distribution range of the large-scale forgings are measured quickly and accurately, and the method has very important theoretical significance and practical value for improving the forging quality and efficiency of the large-scale forgings and reducing the material processing allowance.
However, most of the forging environments of large forgings are extremely severe, and in order to obtain the information of the size and the temperature distribution state of the large forgings for further processing and making up the defects, workers need to manually measure the specific size and other information of the workpiece at high temperature of thousands of degrees centigrade.
At present, in the forging production factory in China, workers usually hold simple tools such as calipers and measuring rods by hands to measure the size of the forging in a hot state in a direct contact mode, as shown in figure 1. The method requires workers to approach a high-temperature target, great potential safety hazards exist, the larger the measured forging is, the greater the measurement difficulty is, and the more the measurement precision can not be guaranteed. The casting level and the automation degree of the large forging are seriously reduced.
Disclosure of Invention
Aiming at the characteristics of the large-sized high-temperature forging and the problems in measurement at present, the invention aims to provide the high-precision intelligent measuring instrument for the high-temperature forging, which realizes the non-contact high-precision measurement of the length, the diameter and the temperature distribution within the safe distance of the high-temperature forging through a human vision bionic technology, an internal/external orientation element calibration technology and a thermal radiation calibration technology.
In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problem is as follows: the utility model provides a high accuracy intelligent measuring apparatu of high temperature forging, includes front end data acquisition equipment and the rear end integrated processing host computer of taking human-computer interaction interface, front end data acquisition equipment include structure optical module, front end data processing module and the infrared imaging temperature measurement subassembly and two image acquisition modules of being connected with front end data processing module, front end data processing module be connected with the rear end integrated processing host computer, image acquisition module add the 4K camera of green narrowband optical filter for the camera lens, front end data processing module still include power conversion module for connection structure optical module, image acquisition module, infrared imaging temperature measurement subassembly and front end data processing module.
The invention also aims to provide a high-precision intelligent measuring method for high-temperature forgings, which comprises the following steps
The method comprises the following steps of firstly, calibrating internal/external orientation elements of a plurality of image acquisition modules by combining a three-dimensional control field with a DLT algorithm:
the method comprises the following steps of placing front-end data acquisition equipment in a three-dimensional control field, carrying out image acquisition on a high-temperature forging through an image acquisition module, and obtaining internal and external orientation elements and optical distortion coefficients of an image acquisition module at the shooting moment by utilizing the following collinear condition equations through object space coordinates and image space coordinates of control points on an image:
wherein,
in the formula, x and y are image plane coordinates of the image point; x is the number of0，y0F is the internal orientation element of the image; xS，YS，ZSThe object space coordinates of the camera stations; xA，YA，ZAIs the object space coordinate of the object space point; a isi，bi，ci(i = 1,2, 3) is 9 direction cosines consisting of 3 external orientation angle elements of the image;
step two, image preprocessing:
the laser of the structural optical module firstly emits laser lines which are weak in intensity and harmless to direct eye radiation, assists in judging whether the measuring instruments are parallel or not, and then emits high-intensity cross laser lines at the moment of imaging to ensure that the cross laser lines are parallel to the upper edge and the lower edge of a forging piece, so that an image acquisition module acquires 4K images containing clear laser lines; converting the collected color image into an HSV (hue, saturation, value) domain, extracting a green component of the image from the HSV image, and performing histogram equalization on the green component single-channel image to improve the contrast and brightness of the image;
step three, extracting the pixel coordinates of the laser line end points:
the operator selects an approximate range of the disconnection point from the 4K image frame, then amplifies the selected range through the human-computer interaction interface, selects the approximate range again and amplifies the approximate range until the range of the disconnection point is selected and extracted for the third time; automatically extracting edge pixels of disconnected points in an extraction range through a Radio detection operator, and splicing all pixel points into a complete straight line through Hough transformation; fitting the pixels on the straight line by adopting a random sampling consistency algorithm (RANSAC) so that the straight line can contain the most pixels; calculating the coordinates of the intersection points of the straight line of the edge of the laser line and the straight lines of the left edge and the right edge of the forge piece, and then taking the mean value of the coordinates of the two points as the coordinates of the matching points;
step four, size measurement based on binocular vision bionic technology: enabling the cross laser line to be parallel to the upper edge and the lower edge of the forging, and calculating each size through projection of the laser line on the surface of the forging;
step five, infrared thermal imaging temperature measurement based on thermal radiation calibration: the non-contact high-precision measurement of the temperature distribution in the safe distance of the high-temperature forge piece is realized.
Further, the extraction of the edge pixels by the Radio detection operator in the third step includes the following steps: setting a 5 × 5 Ratio operator template in the vertical and horizontal directions of the edge of the forging respectively, firstly calculating the average pixel value of each region Ri as Ai, and then calculating the edge detection response functions f12 and f13 of the middle region R1 and the two domain regions R2 and R3 respectively as follows:
and taking the smaller of the edge response functions as a corresponding function F of the line feature, finally obtaining two corresponding functions F0 and F90 of the horizontal line feature and the vertical line feature, taking the larger value of F0 and F90 as the final line feature response function Fm, and finally judging that if Fm is larger than Fth, the pixel is considered as an edge pixel point according to a set threshold value Fth.
Further, the hough transform in the third step is to convert the pixel points in the rectangular coordinate system of the 4K image to the cosine lines in the polar coordinate system, count the points passing the cosine lines most, and then convert the points to the rectangular coordinate system to form a straight line containing the pixel points most.
The invention has the beneficial effects that:
the structural optical module emits laser lines which are weak in intensity and harmless to direct eye radiation before measurement, early preparation work is completed by utilizing the laser lines, and during measurement, a laser is controlled to emit high-intensity laser lines at the moment of imaging, so that a camera can acquire images containing clear laser lines, and further measurement is facilitated;
2, the invention adopts the technology of calibrating the internal and external orientation elements of the image acquisition module based on the three-dimensional control field, so as to realize the micron-scale calibration of the internal and external orientation elements of the sensor;
3, the invention adopts a semi-automatic extraction technology under the assistance of three manual levels, firstly, the image is preprocessed to effectively improve the image quality and the contrast, then, a Ratio template matching algorithm is adopted to extract edge pixel points in a high noise environment, then, a Hough line detection is adopted to recover edge lines, finally, a line is fitted through a random consistency sampling algorithm and matching points are calculated, and the sub-pixel level extraction of the pixel coordinates of the laser line end points on the image is realized;
4, the device integrates a 4K large-view-field image acquisition module, a structural optical module and an infrared imaging temperature measurement assembly, is friendly in man-machine interface, compact in structure, high in reliability and convenient to use, and can effectively improve the measurement efficiency and guarantee the personnel safety.
Drawings
FIG. 1 is a commonly used forging measurement: a is measuring rod measurement, and b is caliper measurement;
FIG. 2 is a system schematic of the meter of the present invention;
FIG. 3 is a front layout view of the meter of the present invention;
FIG. 4 is a field diagram of a three-dimensional control field of the present invention;
FIG. 5 is a flow chart of a measurement method of the present invention;
FIG. 6 is a flow chart of the matching point extraction process of the present invention;
in FIG. 7, a and b are the horizontal and vertical Ratio algorithm diagrams of the present invention, respectively;
FIG. 8 is a schematic representation of a forging profile measured by the present invention;
FIG. 9 is a diagram of the projection effect of structured light on a cylinder;
FIG. 10 is a orthographic camera solution geometry of the present invention;
fig. 11 is an effect diagram of an imaging infrared thermometer.
Detailed Description
The invention will be further described with reference to the accompanying drawings.
The invention provides a high-precision intelligent measuring instrument for high-temperature forgings, aiming at the defects that workers need to approach a high-temperature target and have great potential safety hazards, the measuring difficulty is higher when the measured forgings are larger, and the measuring precision cannot be ensured, the system schematic diagram is shown in figure 2, the high-precision intelligent measuring instrument comprises front-end data acquisition equipment and a rear-end comprehensive processing host with a man-machine interaction interface, the front-end data acquisition equipment comprises a structural optical module, a front-end data processing module, an infrared imaging temperature measurement assembly and a plurality of image acquisition modules, the infrared imaging temperature measurement assembly and the image acquisition modules are connected with the front-end data processing module, the image acquisition modules are 4K cameras with green narrow-band optical filters added in front of lenses, the front-end data processing module is connected with the rear-end comprehensive processing host, and the front-end data processing module also comprises a power supply conversion module for connecting, The image acquisition module, the infrared imaging temperature measurement component and the front end data processing module are shown in the overall appearance figure of fig. 3.
For the safety of furthest protection people's eye, the host computer sets up structure light laser instrument power adjustment button, and the transmitting strength is relatively weak, to the harmless laser line of eye direct projection before measuring, utilizes this laser line to accomplish preparation work earlier stage, and during the measurement, the control laser instrument is at the laser line of the high strength of formation of image transmission in the twinkling of an eye, makes the camera can gather the image that contains clear laser line, is convenient for further measure.
The measuring instrument comprises the following steps when the high-precision intelligent measurement is carried out on the high-temperature forge piece:
1, calibrating internal and external orientation elements of a 4K camera based on a three-dimensional control field: the 4K image acquisition module is installed inside the front end data acquisition equipment, because every module is inside all to have lens distortion, target surface and optical axis out of plumb, focus/like principal point error, and the position gesture between two sensors also has the error, and these factors influence the measuring result of binocular vision greatly, consequently this patent adopts three-dimensional control field to combine DLT algorithm realization 4K camera in/outside orientation element's calibration.
The three-dimensional control field of the invention is shown in figure 4, the front-end data acquisition equipment is placed in the control field for image acquisition, when the image contains enough control points, the internal and external orientation elements and the optical distortion coefficient at the shooting moment of the 4K camera can be obtained by the object side coordinate and the image side coordinate of the control points and by utilizing a collinear condition equation. Wherein, the optical distortion coefficient comprises a radial distortion coefficient and an eccentric distortion coefficient, the radial distortion is that the image point deviates from the accurate position along the radial direction, and the eccentric distortion is the distortion caused by the inconsistency of the optical center and the geometry. The model used for calibration is a collinearity conditional equation, and the common expression form is as follows:
wherein,
and 2, image processing and feature extraction.
The system controls the laser of the structural optical module to emit laser through a computer board card in a rear end comprehensive processing host, the computer board card can control the intensity of the laser through voltage regulation, a laser line which is weak in intensity and harmless to direct eye radiation is emitted before measurement, and whether the laser line is parallel to a horizontal line on a wall surface or not can be judged in an auxiliary mode through the laser line.
During measurement, the computer board card controls the laser to emit high-intensity laser lines at the moment of imaging, so that the 4K camera can acquire images containing clear laser lines.
At the moment, the laser line forms sharp end points at the edge or the shape change of the forging, and the size of the forging can be accurately measured by calculating the distance between the end points. Therefore, image preprocessing and characteristic point extraction of laser lines on the edges of forgings need to be solved firstly.
Because the green narrow-band filter is added in front of the 4K camera lens, the brightness and the contrast of the collected image are obviously low, the image is preprocessed, the brightness and the contrast of the image are improved, an operator can easily see the broken part of the laser line on the edge of the forged piece, and manual auxiliary extraction is finished.
The image preprocessing steps are as follows:
1) and converting the acquired color image into an HSV domain.
2) The green component of the image is extracted in the HSV image.
3) And carrying out histogram equalization on the green component single-channel image to improve the contrast and brightness of the image.
After the image preprocessing is completed, manually assisted extraction of the laser line break points at the edge of the forge piece needs to be further completed.
And 3, finishing manual auxiliary extraction of the laser line breaking points on the edges of the forged pieces by visual operation of an operator.
Considering that the difference between the resolution of a human-computer interface image display area of the rear-end comprehensive processing host and the resolution of an image collected by the 4K camera is large, the method adopts a three-level manual assistance strategy, namely, an operator selects an approximate range of a disconnected point from a 4K image, then a human-computer interaction interface of the upper computer automatically amplifies the selected range, the operator selects the approximate range again in the range and repeats the operation three times, the method can ensure that the extraction range is limited to a smaller range by the operator, the extraction precision and stability of the disconnected point can be greatly improved, and therefore the measurement precision is improved.
In the extraction range limited by the operator, the disconnection point at the sub-pixel level needs to be automatically extracted, and the method adopted in the patent comprises the following steps: according to the method, firstly, the Radio detection operator is adopted to extract edge pixels, then, the forge piece and the laser line pixels are spliced into a straight line through improved rapid Hough transformation, then the straight line is used for approximately fitting the forge piece edge and the laser line edge, finally, intersection points between the edge lines and the forge piece edge lines of the left side and the right side of the laser line are calculated, and the sub-pixel coordinates of the center point of the intersection points are calculated to serve as final matching points. The whole measuring process flow is shown in fig. 5, and the matching point extracting process is shown in fig. 6.
1) Extraction of edge pixels by Radio detection operator
Because the field environment is bad for the forge piece measurement, and the surface of the high-temperature forge piece can rapidly generate an irregular oxide layer due to temperature change during measurement, a large amount of background noise is contained in the collected image, and a large amount of noise edges are generated by adopting commonly used operators such as canny and sobel to extract the edges, so that the straight line extraction is difficult to further carry out, and therefore the method adopts the Ratio detection operator to extract the edge pixel points, and effectively utilizes the horizontal and vertical characteristics of the laser line and the forge piece edge line in the application scene.
The Ratio operator is an improved mean value proportion operator, the mean value is obtained in the field of the central pixel, the noise interference can be effectively reduced through the mean value, the calculation result is the minimum value of the mean value Ratio of the two fields around the central pixel point, and the matching calculation can be carried out through a manually designed template.
In the application scene of this patent, the forging is generally placed horizontally, and the horizontal line of laser line cross is parallel with the forging, therefore the forging edge that we paid attention to and laser line edge are horizontal and vertical edge.
Therefore, in this patent, we design a Ratio operator template with 5 × 5 in both the vertical direction and the horizontal direction, as shown in fig. 7.
First, the average pixel value of each region Ri is calculated as Ai, and then the edge detection response functions f12 and f13 of the middle region R1 and the two domain regions R2 and R3 are calculated, respectively, as follows:
and taking the smaller of the edge response functions as a corresponding function F of the line feature, finally obtaining two corresponding functions F0 and F90 of the horizontal line feature and the vertical line feature, taking the larger value of F0 and F90 as the final response function Fm of the line feature, and finally judging that if Fm > Fth, the pixel is considered as an edge pixel point according to a set threshold value Fth.
2) And performing Hough transform linear splicing.
After all the pixels on the edges of the forge pieces and the power lines are obtained, the pixels need to be further spliced into a complete straight line edge, and improved Hough transformation is adopted for straight line detection.
The Hough transform converts the rectangular coordinate system into the polar coordinate system for detection, the straight line in the original image is converted into the pixel point under the polar coordinate system, and the pixel point in the original image is converted into the cosine line under the polar coordinate system, so that the straight line containing the most pixel points is converted into the rectangular coordinate system only by counting the most cosine points under the polar coordinate system.
3) Straight line fitting
In the last step, because a plurality of straight lines can be fitted on one edge due to the existence of noise, the method can fit the straight lines of the detected pixels on the straight lines by adopting a random sampling consistency algorithm (RANSAC), so that the fitted straight lines can contain the most edge straight line pixels.
4) And calculating the coordinates of the intersection points of the straight lines of the left edge and the right edge of the laser line and the edge of the forging piece, and then taking the mean value of the coordinates of the two points as the coordinates of the matching point.
And 4, binocular measurement.
Taking a typical forging with a flange as an example, as shown in fig. 8, the required dimensions of the forging with the shape include lengths L1, L2 and a diameter D.
The projection of the emergent light of the structural light module on the surface of the forging is shown in fig. 9, and the length L1 can be calculated through S1 and S7, and the length L2 can be calculated through S2 and S6. Since the laser is projected onto the cylinder as shown in fig. 8, the diameter of the cylinder needs to be obtained by three-point fitting, from which the diameter D can be calculated by S3, S5, S4.
According to the calculation of the method, the straight lines S1 and S7 in the graph 8 are required to be parallel to the central line of the forge piece, so that the measuring position of the forge piece needs to be planned in advance, the direction of the central line of the forge piece is marked on the wall surface behind the measuring position, and the laser of the structural optical module can be adjusted in advance.
In the system, two straight lines emitted by the structural optical module are vertical, so that the laser line is only required to be parallel to the upper edge and the lower edge of the forge piece when the size of the forge piece is calculated by adopting the principle. The measured strong laser line is adjusted according to the horizontal line of the wall surface, so that the strong laser line is parallel to the horizontal line of the wall surface only when the forge piece is hung.
The laser reference line end position calculation adopts a photogrammetry principle, takes a straight photography mode as an example, and is shown in fig. 9: the left photographing center is taken as the origin of S1, the connecting line S1-S2 (photographing base line) of the two photographing centers is taken as the X axis, a point A (X, Y, Z) is arranged on the object side, and the corresponding image points on the two photographs p1 and p2 are a1(X1, Y1) and a2(X2 and Y2). In the figure, H denotes an imaging distance (= -Z), B denotes an imaging baseline, f denotes a camera main distance, and p denotes left-right parallax (x 1-x 2).
According to the principle of photogrammetry:
and 5, infrared temperature measurement.
When the temperature of an object is higher than absolute zero, the molecular motion inside the object can emit electromagnetic waves outwards in a heat radiation mode, wherein the energy is strongest in an infrared band (0.75-100 um), and an infrared temperature measurement technology is developed based on the principle. The infrared temperature measurement technology is non-contact passive temperature measurement, and compared with the traditional temperature measurement technology, the infrared temperature measurement technology has the advantages of no interference to a temperature measurement field, high accuracy and precision and real-time measurement.
The infrared thermometer adopted by the scheme is an imaging type thermometer, can image the infrared radiation amount of a scene in a field range, and the rear end can measure the temperature of a certain area or a certain point aiming at a single frame image, so that the temperature statistical analysis is realized, as shown in fig. 11.
Finally, the high-precision intelligent measuring instrument for the high-temperature forging is adopted, so that high size and temperature measuring precision are obtained in an actual scene, and the field use requirement is met. The distance between the front-end data acquisition equipment and the forge piece is controlled to be between 3 and 7 meters, the temperature measurement error within the temperature range of 800-1200 ℃ is less than or equal to 20 ℃, and the dimensional accuracy under the obtained typical distance is shown in the table.
The above-described embodiments are merely illustrative of the principles and effects of the present invention, and some embodiments may be applied, and it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the inventive concept of the present invention, and these embodiments are within the scope of the present invention.
Claims (4)
1. The utility model provides a high accuracy intelligent measuring instrument of high temperature forging which characterized in that: the intelligent camera comprises front-end data acquisition equipment and a rear-end comprehensive processing host with a man-machine interaction interface, wherein the front-end data acquisition equipment comprises a structural optical module, a front-end data processing module, an infrared imaging temperature measurement component and two image acquisition modules, the infrared imaging temperature measurement component and the two image acquisition modules are connected with the front-end data processing module, the front-end data processing module is connected with the rear-end comprehensive processing host, the image acquisition module is a 4K camera with a green narrow-band optical filter added to a lens, and the front-end data processing module further comprises a power supply conversion module for connecting the structural optical module, the image acquisition module, the infrared imaging temperature measurement component and the front-end data processing module.
2. A high-precision intelligent measurement method for a high-temperature forging, which is based on the measurement instrument of claim 1, is characterized in that: comprises the following steps
The method comprises the following steps of firstly, calibrating internal/external orientation elements of a plurality of image acquisition modules by combining a three-dimensional control field with a DLT algorithm:
the method comprises the following steps of placing front-end data acquisition equipment in a three-dimensional control field, carrying out image acquisition on a high-temperature forging through an image acquisition module, and obtaining internal and external orientation elements and optical distortion coefficients of an image acquisition module at the shooting moment by utilizing the following collinear condition equations through object space coordinates and image space coordinates of control points on an image:
wherein,
in the formula, x and y are image plane coordinates of the image point; x is the number of0，y0F is the internal orientation element of the image; xS，YS，ZSThe object space coordinates of the camera stations; xA，YA，ZAIs the object space coordinate of the object space point; a isi，bi，ci(i = 1,2, 3) is 9 direction cosines consisting of 3 external orientation angle elements of the image;
step two, image preprocessing:
the laser of the structural optical module firstly emits laser lines which are weak in intensity and harmless to direct eye radiation, assists in judging whether the measuring instruments are parallel or not, and then emits high-intensity cross laser lines at the moment of imaging to ensure that the cross laser lines are parallel to the upper edge and the lower edge of a forging piece, so that an image acquisition module acquires 4K images containing clear laser lines; converting the collected color image into an HSV (hue, saturation, value) domain, extracting a green component of the image from the HSV image, and performing histogram equalization on the green component single-channel image to improve the contrast and brightness of the image;
step three, extracting the pixel coordinates of the laser line end points:
the operator selects an approximate range of the disconnection point from the 4K image frame, then amplifies the selected range through the human-computer interaction interface, selects the approximate range again and amplifies the approximate range until the range of the disconnection point is selected and extracted for the third time; automatically extracting edge pixels of disconnected points in an extraction range through a Radio detection operator, and splicing all pixel points into a complete straight line through Hough transformation; fitting the pixel points on the straight line by adopting a random sampling consistency algorithm, so that the straight line can contain the most pixel points; calculating the coordinates of the intersection points of the straight line of the edge of the laser line and the straight lines of the left edge and the right edge of the forge piece, and then taking the mean value of the coordinates of the two points as the coordinates of the matching points;
step four, enabling the cross laser line to be parallel to the upper edge and the lower edge of the forge piece, and calculating each size through projection of the laser line on the surface of the forge piece;
and fifthly, carrying out non-contact high-precision measurement on the temperature distribution of the high-temperature forging piece within a safe distance through the infrared imaging temperature measurement assembly.
3. The high-precision intelligent measurement method for the high-temperature forgings according to claim 2, wherein the step three in which the Radio detection operator extracts the edge pixels comprises the following steps: setting a 5 × 5 Ratio operator template in the vertical and horizontal directions of the edge of the forging respectively, firstly calculating the average pixel value of each region Ri as Ai, and then calculating the edge detection response functions f12 and f13 of the middle region R1 and the two domain regions R2 and R3 respectively as follows:
and taking the smaller of the edge response functions as a corresponding function F of the line feature, and finally obtaining two corresponding functions F0 and F90 of the horizontal line feature and the vertical line feature, wherein the final line feature response function Fm takes the larger value of F0 and F90, and finally, according to a set threshold value Fth, if Fm is larger than Fth, the line feature response function is regarded as an edge pixel point.
4. The high-precision intelligent measuring method for the high-temperature forgings according to claim 2, wherein the Hough transformation in the third step is to convert pixel points in a rectangular coordinate system in the 4K image into cosine lines in a polar coordinate system, count the points passing through the cosine lines at the most, and convert the points into a straight line containing the pixel points at the most in the rectangular coordinate system.
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| CN113641155A (en) * | 2021-07-23 | 2021-11-12 | 连云港杰瑞自动化有限公司 | High-temperature forging detection control system |
| CN113643386A (en) * | 2021-10-13 | 2021-11-12 | 深圳市商汤科技有限公司 | Calibration method and device, electronic equipment and computer readable storage medium |
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